Delivery outcomes and events in subsequent pregnancies after previous anal sphincter injury

Abstract

Objective: To assess the mode of delivery following previous anal sphincter injury (ASI), and to evaluate the perineal outcome following a vaginal birth.

Study design: Retrospective data search of the hospital Patient Access System on patients who delivered following previous ASI from 2010 to 2012. When a second ASI was sustained, additional information was gathered from the patients' medical notes. Continuous variables were described by counts and percentages and analysed using SPSS version 20.

Results: Between January 2010 and July 2012, 138 women with previous ASI delivered at the Rotunda Hospital, of whom 69 (50%) had a spontaneous vaginal delivery (SVD), 13 (9.4%) had an instrumental delivery (11 vacuum, 2 forceps), and 56 (40.6%) had a caesarean section. Of these caesarean sections, 43 (76.8%) were elective, and 13 (23.2%) were emergency. Of the 82 vaginally delivered patients, the majority had a second degree perineal tear or minor lacerations (54/82 and 14/82 respectively) but 11 had a third degree perineal tear following an SVD - a recurrence risk of 13.4%. There was no significant difference in the average birthweight between patients who sustained a second ASI (3644g) compared to those who did not (3680g). None of the patients who had a second ASI developed faecal incontinence symptoms postnatally: two patients developed flatal incontinence which resolved with physiotherapy.

Conclusion: This study highlights the importance of individualised antenatal assessment in patients with a previous ASI. They may have a personal preference when considering their mode of delivery. A specialist clinic affords them the opportunity for a detailed discussion. In this study, 86.5% of women who delivered their subsequent baby vaginally did not sustain an ASI, while 13.4% had a repeat ASI following vaginal birth. It is therefore important to counsel regarding the incidence of repeat ASI, but also to emphasise that it is generally impossible to confidently predict recurrence antenatally.

Keywords: Anal sphincter injury; Episiotomoy; Mode of delivery; Previous perineal tear; Recurrence; Vaginal delivery.